To solve the problem of network QoS degradation caused by the limited energy, fast movement and data of UAV Ad-Hoc network nodes, the improved firefly multipath routing algorithm (AOMDV-FMRA) was put forward. Firstly, in order to reduce the influence of speed on the path stability, a boundary evaluation factor is introduced into the route discovery process to adapt to the topology change. Then, the reverse route is selected according to the load information of the nodes on the path. Finally, the energy evaluation parameters are mapped to the firefly algorithm to process the collected path energy information as the basis for flow allocation. Experimental results show that, compared with AODV and AOMDV, in the environment of high node speed and large network traffic, the algorithm has good performance in aspects of end-to-end delay, network survival time, delivery success rate and routing cost.